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Old 02-05-2019, 11:56 PM   #1
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
Posts: 9
Stumbling idle when stopping.

Hello all,

I'm new here and recently was gifted a 2007 hatch with a few issues. Most were easy to remedy, squealing serpentine belt, hazy headlights, out of round rear drums and things of that nature. One thing that has eluded me has been an idle issue that driving me nuts.

While coming to a stop the car feels like it is going to stall. Just before a complete stop, no matter how brief, the idle will dip to sub 500 RPM, I'm guessing that figure due to it being auto with no tach. It gets to where it feels like it will stall then it will recover. While sitting at idle the RPM will jump around. It has yet to die on me, but feels like it wants to 100% of the time while stopping.

Here are some things I have done to try and fix the issue.

New air filter
New plugs
Cleaned MAF sensor
Cleaned TB without removing it, therefore I'm not sure of the condition behind the butterfly. Used a cinder block to open the TB with the key on to clean around the plenum, but not behind the butterfly valve.

The car has 188k miles on it and I'm very impressed with the mileage over my 2010 Nissan Titan 4x4.

I have seen many posts similar to this but not exact and all of them fizzeled out before a solution was given or found.

I know a fair amount around a car, but when it comes to fuel injection I'm kinda lost. If I'm overlooking anything, please give me some guidance. There is a lot of info on this forum and I hope to get many years of help and offer a lot in the future.

Thanks in advance,
Jeremy
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Old 02-06-2019, 01:49 AM   #2
komichal
 
Drives: Yaris 2007 1.3 2SZFE 64kW
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Location: CZ
Posts: 133
Hello there!
My Yaris is also humming on very low RPMs when idling. AFAIK this is normal for this car.
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Old 02-06-2019, 09:22 AM   #3
firebird1999us
 
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Join Date: Oct 2008
Location: Georgia
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I had a similar issue but it turned out the alternator that I had recently replaced was not tightened down enough. I had cranked down the bottom bolt pretty tight but it was still not as tight as it needed to be. My mechanic got it on there tight and the car stopped a good bit of what I felt was mechanical vibration. I felt like I was in danger of overtigtening but I guess it had a bit to go.

My car has 350k+ on it... we also discovered through the whole process that the vibration I thought was an idle issue was actually the motor/transmission mounts failing. I was only getting a vibration when the car was in gear and I had the AC on at a stoplight when the car was under load. Now that we've pinpointed the mounts failing I can feel that the vibration is coming from the direction of the transmission and lower motor mounts.

There's also an Idle Control Valve that can be problematic too... I believe it's located under the throttle body? Those are fairly delicate and expensive to replace per some of the info I've read so be careful if you try to clean it!
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Old 02-06-2019, 09:30 AM   #4
dogsridewith
 
Drives: 2007 2-door hatchback
Join Date: Jul 2016
Location: USAnotCA
Posts: 733
Yaris idle speed measure multimeter frequency

Manual tranny warmed-up idle is 600 rpm. Mine was, and likely is, exact, per a multimeter set on "frequency" standing up in the driver's side dash cupholder. (Yes, that isn't a little glove-box as it might seem...notice how it will crush contents when closing.)
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Old 02-06-2019, 12:25 PM   #5
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
Posts: 9
Quote:
Originally Posted by firebird1999us View Post
I had a similar issue but it turned out the alternator that I had recently replaced was not tightened down enough. I had cranked down the bottom bolt pretty tight but it was still not as tight as it needed to be. My mechanic got it on there tight and the car stopped a good bit of what I felt was mechanical vibration. I felt like I was in danger of overtigtening but I guess it had a bit to go.

My car has 350k+ on it... we also discovered through the whole process that the vibration I thought was an idle issue was actually the motor/transmission mounts failing. I was only getting a vibration when the car was in gear and I had the AC on at a stoplight when the car was under load. Now that we've pinpointed the mounts failing I can feel that the vibration is coming from the direction of the transmission and lower motor mounts.

There's also an Idle Control Valve that can be problematic too... I believe it's located under the throttle body? Those are fairly delicate and expensive to replace per some of the info I've read so be careful if you try to clean it!
Thanks for the info Firebird,

When I got the vehicle I needed to replace the alternator tensioning bar since the original was cracked on the top and was making the alternator sit at an angle making the worst belt squeal ever. When I removed the alternator it had rubber dust all over the side from the last belt being chewed up. So I know the alternator is nice and tight and charging the system as well.

The car belonged to my mother in law then my brother in law and I was their "mechanic" for the last 6 years. I replaced the motor mounts about 3 years ago around 145k miles so they are good as well.

When I did the throttle body cleaning I didn't see an Idle control valve like on older Toyotas I have worked on. I think since the TB for the yaris is throttle by wire, it simply adjusts the butterfly to make an air change at idle. When I cleaned the TB I didn't notice an IAC vent in the plenum.

Those would all make the vehicle feel like it is shaking for sure, but the only one I would think of causing the near stalling would be the TB. I think if the weather holds up I will remove it and clean it on both sides to see if a difference is made.

Thanks again!
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Old 02-06-2019, 12:29 PM   #6
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
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Quote:
Originally Posted by dogsridewith View Post
Manual tranny warmed-up idle is 600 rpm. Mine was, and likely is, exact, per a multimeter set on "frequency" standing up in the driver's side dash cupholder. (Yes, that isn't a little glove-box as it might seem...notice how it will crush contents when closing.)
I saw this the other day, but can't remember where I saw it. I need to know which pin on the OBD connector to connect the positive lead to. I love the idea of using a multimeter as a tach! Also, when you say frequency I'm assuming you mean volts AC.
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Old 02-06-2019, 02:07 PM   #7
dogsridewith
 
Drives: 2007 2-door hatchback
Join Date: Jul 2016
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Posts: 733
Multimeter tachometer frequency dwell Extech

This decade or two old Extech tach is auto-ranging in all functions and has one rotary knob for two off positions and 12 functions. One is labeled FREQ and % (where the little manual said that % is duty-cycle, which I was able to use to read dwell on a not-electronic V8 points distributor...33.3% being 30 degrees dwell, I recall)

On frequency-to-rpm conversion, you've got 60 seconds/minute and the OBD pin is making two signals per crank revolution. It is one of the end pins in two rows of 8. (Search terms tachometer and OBDII should get you to threads on this) I got ground from the cigar lighter socket.

I liked seeing how idle RPM worked through warm-up, and help getting my ear calibrated for rpm. (The rev limiter spec is 6000 rpm. I like to use 5000 and get there once in awhile for engine health...usually merging or entering a traffic stream in second or third and then skipping a gear in the upshift.) Really just need to consider owner's manual "max speed in gears" for 2 and 3 for most all driving conditions.
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Old 02-10-2019, 09:25 AM   #8
2bz
 
Drives: 2008 Yaris 3DR Hatch MT
Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 76
OP: Have you:

1. Cleaned the idle air control valve (under the TB)?
2. Cleaned the VVT oil control valve?
3. Replaced the oil control valve filter?
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Old 02-10-2019, 12:16 PM   #9
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
Posts: 9
Quote:
Originally Posted by 2bz View Post
OP: Have you:

1. Cleaned the idle air control valve (under the TB)?
2. Cleaned the VVT oil control valve?
3. Replaced the oil control valve filter?
I haven't done any of that yet. I'm planning on taking the TB off today and rooting around in there. I assumed there was no IAC due to it being throttle by wire.

I do have another question. If the TB is removed from the vehicle, can the butterfly be moved slowly to clean the back side of it and the edge? I have seen videos and forum posts saying it's ok to do so, while others say to never manipulate the butterfly EVER. I won't be flipping it rapidly, just slowly open it to clean it thoroughly, while trying to not strip the gears inside.
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Old 02-10-2019, 12:28 PM   #10
2bz
 
Drives: 2008 Yaris 3DR Hatch MT
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Quote:
Originally Posted by Phatdonkey78 View Post
I haven't done any of that yet. I'm planning on taking the TB off today and rooting around in there. I assumed there was no IAC due to it being throttle by wire.

I do have another question. If the TB is removed from the vehicle, can the butterfly be moved slowly to clean the back side of it and the edge? I have seen videos and forum posts saying it's ok to do so, while others say to never manipulate the butterfly EVER. I won't be flipping it rapidly, just slowly open it to clean it thoroughly, while trying to not strip the gears inside.
No IAC on this model. Sorry, my bad.
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Old 02-16-2019, 09:03 PM   #11
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
Posts: 9
Today I got the throttle body gasket and got to work. Removed the TB and cleaned it front and back. Installed new gasket and slapped it all back together. It is a lot more responsive and the stumbling idle when braking is gone now.

Next task is passenger lower control arm replacement. Went to get an alignment and the ball joint is mangled pretty good.
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Old 02-16-2019, 09:12 PM   #12
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
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Here are the before and after pics of the back side of the TB. It was pretty filthy.
Attached Images
File Type: jpg 20190216_200407_resized.jpg (300.9 KB, 49 views)
File Type: jpg 20190216_200606_resized.jpg (203.2 KB, 49 views)
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Old 02-17-2019, 09:34 AM   #13
2bz
 
Drives: 2008 Yaris 3DR Hatch MT
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Location: Harrisburg, PA
Posts: 76
Looks good! The tolerance between the butterfly and the bore on the TB is DNZ (damn near zero), so this should certainly help. I have installed an oil catch filter after the PCV and now my TB stays squeaky clean.

Last edited by 2bz; 02-17-2019 at 09:56 AM.
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Old 02-17-2019, 01:41 PM   #14
Phatdonkey78
 
Drives: 2007 Hatch
Join Date: Feb 2019
Location: Norristown, PA
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Quote:
Originally Posted by 2bz View Post
Looks good! The tolerance between the butterfly and the bore on the TB is DNZ (damn near zero), so this should certainly help. I have installed an oil catch filter after the PCV and now my TB stays squeaky clean.
How often do you drain the catch can? Did you buy one or make your own?
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Old 02-17-2019, 02:49 PM   #15
tmontague
 
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Quote:
Originally Posted by Phatdonkey78 View Post
How often do you drain the catch can? Did you buy one or make your own?
I drain mine every week (approx 150 km) and 3-4 ounces come out during the middle of winter. In the summer it is mostly oil and little water and I drain it much less
Probably around 4 ounces every 6-10k km
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Old 02-17-2019, 03:49 PM   #16
2bz
 
Drives: 2008 Yaris 3DR Hatch MT
Join Date: Dec 2018
Location: Harrisburg, PA
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Quote:
Originally Posted by Phatdonkey78 View Post
How often do you drain the catch can? Did you buy one or make your own?
I spliced this compressor air filter in with a couple of 3/8" barbs.


https://www.harborfreight.com/mini-a...ter-68225.html

https://www.harborfreight.com/38-in-...ece-63957.html
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Old 02-17-2019, 03:56 PM   #17
2bz
 
Drives: 2008 Yaris 3DR Hatch MT
Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 76
Quote:
Originally Posted by Phatdonkey78 View Post
How often do you drain the catch can? Did you buy one or make your own?
I spliced this compressor air filter in with a couple of 3/8" barbs.


https://www.harborfreight.com/mini-a...ter-68225.html

https://www.harborfreight.com/38-in-...ece-63957.html
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